Joe Manchin flip-flops. What caused Joe Manchin to cave in to pressure and vote to betray his constituents?

Democrat Sen. Joe Manchin has been opposed to supporting Biden's Build Back Better bill for a while, but he has now caved. Sen. Manchin and other Democrats have even said in the past that the last thing you want to do in a recession is increase taxes. Why did Joe Manchin flip flop on this?